[en] Morbid obesity is a crucial risk factor in the development of type 2 diabetes and is often associated with a metabolic syndrome closely linked to insulin resistance. This case report illustrates the natural history of morbid obesity, starting during the adolescence and ending with an extremely severe type 2 diabetes at the age of 40. Numerous attempts of weight loss with various medical approaches failed and diabetes mellitus rapidly became insulin-requiring in a context of extreme insulin resistance. Finally, the patient was submitted to a gastric bypass which resulted in a drastic weight loss over 50 kg during the year following surgery without any significant side-effects or complications. Type 2 diabetes almost disappeared and the classical markers of insulin resistance were markedly improved. This clinical case clearly demonstrates that successful management of obesity with bariatric surgery can reverse severe type 2 diabetes.